2 TT house batteries wired in parallel....A frame mountedFrom a portable solar panel kit with charge controller.Instead of gator clips on the batteries, use ring connectors to the posts.Proper connection scheme?....one ring on one batteries positive and the other ring on batt# 2 negative?

Or both rings on the pos/neg of a single batt and let the parallel connection send charge to both?

Seems to me, a hardwired ring connection that can be left on the batteries is a better deal than gator clips?

Not true! As long as the jumper cable is in place on the neg.terminals of both batteries and the jumper cable is in place on the pos. terminals....both terminals are at the same potential with respect to the other terminals.

markbarendt

Batteries that are wired in parallel have all the positives posts tied together, similarly all the negatives are tied together. This works regardless of how many batteries are in the bank.

Given that, it doesn't really matter which specific post you tie to.

Electricity will find the path of least resistance regardless of which battery post you tie to. Balance of the batteries is affected more by defects in the system than where you place the charge wires. For example if the wires tying the batteries together are too small that would be considered a design defect and that can cause charge imbalances. Any defect should be fixed, post placement choice is not a fix.

First of all, there's a night and day difference between a parallel hookup and a series hookup. A parallel hookup allows you to get the same 12VDC , but doubles your A/H availability (if you are using two batteries). If two 6 volt (think golf cart) batteries are hooked in series, you get 12VDC and the same A/H

Secondly, that drawing/picture in the above post is is fine, BUT the explanation is totally wrong. Current flow happens when:1. There is a complete circuit (nothing in the circuit path open)2. When there is a potential applied to the circuit (12 volts in our case)3. The resistance in the circuit is not so great to overcome or stop current flow with the applied voltage or potential.

What you are failing to understand is that any point of the negative side of the circuit is at the same electrical potential as any other point in the negative side of the circuit. And, conversely, any point of the positive side of the circuit is at the same electrical potential as any other point in the positive side of the circuit. Of course this is given the fact that there are no loose connections anywhere or corroded terminals, or some defect inside one of the batteries. Any other explanation DEFY ohms law......and that ain't happening.

A parallel hookup allows you to get the same 12VDC , but doubles your A/H availability (if you are using two batteries). If two 6 volt (think golf cart) batteries are hooked in series, you get 12VDC and the same A/H

Two (2) 6V batts wired in parallel gets 12V and double or the same Ah as one batt?

markbarendt

Everything I've read indicates that if you attach your battery leads to a single battery that battery will be overworked relative to the other batteries in parallel or series. See image

I fully believe that to be an urban myth.

Charging wires from panels or alternator are typically considerably smaller than the cables that connect the batteries together. That small wire from the charging source is a limiting factor. The big cables between the batteries can handle typically 4 to 8 times more juice so there should be no impediment to either battery doing it's share.

Voltage can be thought of a bit like water pressure in that to charge if your charge source is putting out 14.5 volts and battery A is charged to 14.5 and battery B is at 14 volts only battery B will continue to accept more charge. The charge source simply balanced against battery A.

Happens the same way on discharge if Battery A is at 12 volts and B is at 12.5, B will take more load until they balance.

I beg to differ. It is also said the chain is only as stong as its weakest link. Many places for a weak link to occur in a multiple battery set up. Your scenerio assumes a perfect "chain". Not reality. Too many variables.

In reading the thread word for word, it appeared to me the OP has 2 6v batteries. But he doesn't confirm that fact. He never says type of batteries he has. Sounds to me like everyone is guessing.

I think it's a good time to start again. Lets find out exactly what the OP has in place (Maybe pics?) and help this poor poster out.

« Last Edit: December 29, 2016, 10:47:26 AM by denmarc »

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Mark

1994 Jayco Eagle 370FB on 24 acres of paid off paradise in Michigan.

You have brains in your head. You have feet in your shoes. You can steer yourself any direction you choose.Dr. Seuss

I beg to differ. In reading the thread word for word, it appeared to me the OP has 2 6v batteries. But he doesn't confirm that fact. He never says type of batteries he has. Sounds to me like everyone is guessing.

I think it's a good time to start again.

There is no reason to start anything over. He has TWO 12volt batteries. You could have a dozen of whatever voltage batteries you want to talk about, and if they are all in parallel, you can put the charging leads wherever you want....as long as the negative lead is somewhere on the negative part of the battery array........and the positive lead is somewhere on positive part of the battery array....it makes absolutely NO difference and will charge the battery bank. Obviously, one regular sized battery charger trying to charge 12 batteries in my example is going to take a while, but that is because you now have 12 Times the available Amp/ Hours of just one single battery

And by the way, the original poster has TWO 12 volt batteries.....not 6 volt batteries!

He doesn't state specifically that he has two 12V batteries, but by simple deduction, it's there. A couple of keys to this....1. He has TWO batteries2. He has stated that they are connected in PARALLEL

So this is how I know he has 12V batteries.....

What is the voltage of two (or more) 12 volt batteries connected in parallel................12 VoltsWhat is the voltage of two 6 volt batteries connected in parallel....................6 volts

So now it become crystal clear, as I don't know of any RVs that run on a 6 volt system.....so the obvious answer is two 12 volt batteries. Hope this helps.

markbarendt

I beg to differ. It is also said the chain is only as stong as its weakest link. Many places for a weak link to occur in a multiple battery set up. Your scenerio assumes a perfect "chain". Not reality. Too many variables.

In reading the thread word for word, it appeared to me the OP has 2 6v batteries. But he doesn't confirm that fact. He never says type of batteries he has. Sounds to me like everyone is guessing.

I think it's a good time to start again. Lets find out exactly what the OP has in place (Maybe pics?) and help this poor poster out.

Mark, I don't disagree that problems in the chain can be a problem but I don't assume perfect either, just well maintained and designed.

IMO the myth exists because people don't maintain their systems as often as they should or the builder went cheap.

While I don't disagree with the numbers quoted in your linked article, there is a "practical" realization to live with. For our purpose, using multiple batteries to provide more amp/hours in our RVs. The examples given in the article are splitting hairs....to the extreme. The analogy that I would make is that if your car/truck battery was reading 12.6 volts, as measured with a perfectly calibrated volt meter and you engaged the starter to start the car/truck.....neither you or anyone else could tell the difference between that 12.6 volt battery starting the car and one that reads 12.5 volts. It's no different that you common household voltage variations. I can take a meter out to the breaker panel at my house and read one side of the 240VAC coming into the house and get 124.7volts to the neutral, then read the other hot line to neutral and get 124.2volts......can you tell the difference between the brightness of one light bulb being fed off of one side of the incoming power vs. another light bulb being fed off of the other phase coming in......with a .5 volt difference?

I work as a High Voltage Journeyman Electrician and some of the testing that we do on high voltage breakers and contactors for motor control, involve testing them for contact resistance, phase to ground resistance, and leakage current to ground which tests the amount of current flow to ground with specialized, highly calibrated test instruments. I see readings that are so small that most people would simply ignore them or not even know what it meant. An example of this....while applying 10,000 volts to a high voltage breaker, we measure the amount of leakage current to ground for that particular conductor of the breaker and sometime see as little as 1/10 of one micro-amp...that's .0000001 amp of current. Many times the resistance reading for that part of the breaker might be as high as 8 or 9 teraohms.....and one teraohm is equal to 1,000,000 megaohm....so suffice to say....a very high resistive value.

So, I've said all of that ^^^^^ to say this. For all intents and purpose of hooking up a charger to the battery bank of parallel batteries, it really doesn't matter where you hook it up for our practical use of the batteries in our RVs. Are you really going to see that .0001 voltage drop? Are you really going to see any performance degradation from it? And furthmore, I quit reading the article when I rechecked their math and found some of his published numbers to be wrong. .00012 (cable resistance for 20cm of cable) AND the additional .0002 (connector resistance) plus another .0002 connector reistance does NOT add up to what he said... .0015 ohms. The actual total resistance for what he is talking about...two connections and one length of cable is.... .00012 + .0002 + .0002 = .00052 not .0015. And again, these are very, very, small resistance numbers that in real life, what we are using our batteries in the RV for, have no noticeable effect on our battery charging/usage.

In my world of high voltage breakers and contactors when dealing with 2300V, 4160V, and 13.8KV, those small numbers in the micro amp and teraohm range have significant meaning and will determine whether or not a breaker will safely operate according to IEEE testing standards......in the real world of 12 volt batteries in an RV...........not so much

And then, to top it all off, the O.P. gave us the wrong information in the original post and stated that he had a parallel hookup for his batteries. Turns out, he has two 6 volt batteries that are hooked up in series to provide 12 volts.....and we all know that Ohms law states that the current flow in a series circuit is the same throughout the entire circuit, and that amount of current flow is based on the applied voltage and the total circuit resistance.

Sorry for the very long-winded post, but I felt that some "practical" light should be shed on the subject and information given that will work for our purpose.

And a quick PS......I don't consider this discussion an "argument". To me it is simply a discussion with the hope of coming to some conclusion for our practical use of batteries in our RV's.....a common sense approach if you will.

Is substantial. That's 4 batteries connected in parallel, the 'bottom battery' having both leads connected to it.

Industry standard is connecting one lead to the first battery and the 2nd lead to the last battery, getting these improved, equalized results:The bottom battery provides 26.7 amps of this.The next battery up provides 23.2 amps.The next battery up provides 23.2 amps.The top battery provides 26.7 amps.

That's not to say that I totally disagree with you, because your point about it splitting hairs is accurate. The batteries will eventually equalize no matter how they're connected, and they're also gonna charge just fine. I think the proper wiring's point is that more stress is placed on the first example's first battery, so to protect your battery investment wire it our way iinstead.

Remember though, as I posted above, his resistance numbers didn't add up correctly, which tosses out the validity of what he is saying to a big extent.

Here's the part I'm talking about...

Quote

And furthmore, I quit reading the article when I rechecked their math and found some of his published numbers to be wrong. .00012 (cable resistance for 20cm of cable) AND the additional .0002 (connector resistance) plus another .0002 connector reistance does NOT add up to what he said... .0015 ohms. The actual total resistance for what he is talking about...two connections and one length of cable is.... .00012 + .0002 + .0002 = .00052 not .0015.

And honestly, unless he used some sort of highly calibrated and accurate Test instrument similar to the ones we use in our high voltage testing program where I work, his numbers may be flawed also. I have no way of knowing that is the case though. Just one of our contact resistance testers, which tests down to 1/1,000,000 of an ohm, costs well over $20K. That is the type of test equipment that would be required to come up with some of the resistance numbers that he is touting. They may very well have access to that type of equipment, again, I don't know. But what I do know is that his math is flawed in the above quote, so in my book, he has lost some critical reliability with what he states.

This is what I was wanting to do and by no means am I a electrical engineer, who is wise to the ways of volts, amps and watts.

My camping will be done out west where there is normally ample hours of sun and 90% of this camping will be done without electrical hookups.

I don't have the trailer yet......but close to making a purchase.The trailer "box" is 23 feet on the unit I am considering.

My useage would be minimal of 12V power.....I am single with no dogs, cats or any two legged companions.Lighting, water pump, furnace fan if needed, refer electronics, electronic safety devices, OEM AM-FM-DVD player and the TV....along with a 600W inverter to power a laptop computer and various small electronic devices. Not all at one time.I have zero need for a toaster, hair dryer, a Mr. Coffee maker or any other high draw electrical appliances.

Currently I camp in a truck slide in camper that has a 100W roof mounted solar panel feeding 2 Exide Edge 12V AGM batts in parallel, and is equipped with a 300W inverter that runs a laptop and a portable radio for hours on end with zero issues.

I was planning on getting a 120W GoPower portable solar panel setup to recharge the 2 supplied house batts on the yet to be purchased TT.As an option before taking delivery of this new unit, I can change out the supplied batteries from 2 12V to 2 6V.

My tendency is to replace the supplied 12V batts (take off credit) with 2 Trojan T-105 6 volt units and wire in series to take advantage of increased Ah's and reported battery longevity, over 2 12V units.

Desert_Rat

Remember though, as I posted above, his resistance numbers didn't add up correctly, which tosses out the validity of what he is saying to a big extent.

Here's the part I'm talking about...And honestly, unless he used some sort of highly calibrated and accurate Test instrument similar to the ones we use in our high voltage testing program where I work, his numbers may be flawed also. I have no way of knowing that is the case though. Just one of our contact resistance testers, which tests down to 1/1,000,000 of an ohm, costs well over $20K. That is the type of test equipment that would be required to come up with some of the resistance numbers that he is touting. They may very well have access to that type of equipment, again, I don't know. But what I do know is that his math is flawed in the above quote, so in my book, he has lost some critical reliability with what he states.

I think the additional '0' is just a typo but even if it's not, that bad math is applied to each of the 4 tested wiring schemes.

Desert_Rat

This is what I was wanting to do and by no means am I a electrical engineer, who is wise to the ways of volts, amps and watts.

My camping will be done out west where there is normally ample hours of sun and 90% of this camping will be done without electrical hookups.

I don't have the trailer yet......but close to making a purchase.The trailer "box" is 23 feet on the unit I am considering.

My useage would be minimal of 12V power.....I am single with no dogs, cats or any two legged companions.Lighting, water pump, furnace fan if needed, refer electronics, electronic safety devices, OEM AM-FM-DVD player and the TV....along with a 600W inverter to power a laptop computer and various small electronic devices. Not all at one time.I have zero need for a toaster, hair dryer, a Mr. Coffee maker or any other high draw electrical appliances.

Currently I camp in a truck slide in camper that has a 100W roof mounted solar panel feeding 2 Exide Edge 12V AGM batts in parallel, and is equipped with a 300W inverter that runs a laptop and a portable radio for hours on end with zero issues.

I was planning on getting a 120W GoPower portable solar panel setup to recharge the 2 supplied house batts on the yet to be purchased TT.As an option before taking delivery of this new unit, I can change out the supplied batteries from 2 12V to 2 6V.

My tendency is to replace the supplied 12V batts (take off credit) with 2 Trojan T-105 6 volt units and wire in series to take advantage of increased Ah's and reported battery longevity, over 2 12V units.

Thank you and all comments welcome.

First of all, why change out the Exides for the Trojans? the energy storage on both is basically the same, and although I'd agree that the Trojan is a better battery I don't think it's $300 better. Assuming your Exides are good, I would keep them and buy a 2nd panel with the money. To run all that stuff you'll need at least another panel anyway.